from_numpy_matrix¶
- from_numpy_matrix(A, parallel_edges=False, create_using=None)[source]¶
Returns a graph from numpy matrix.
The numpy matrix is interpreted as an adjacency matrix for the graph.
- Parameters
- Anumpy matrix
An adjacency matrix representation of a graph
- parallel_edgesBoolean
If True,
create_using
is a multigraph, andA
is an integer matrix, then entry (i, j) in the matrix is interpreted as the number of parallel edges joining vertices i and j in the graph. If False, then the entries in the adjacency matrix are interpreted as the weight of a single edge joining the vertices.- create_usingNetworkX graph constructor, optional (default=nx.Graph)
Graph type to create. If graph instance, then cleared before populated.
See also
Notes
For directed graphs, explicitly mention create_using=nx.DiGraph, and entry i,j of A corresponds to an edge from i to j.
If
create_using
isnetworkx.MultiGraph
ornetworkx.MultiDiGraph
,parallel_edges
is True, and the entries ofA
are of typeint
, then this function returns a multigraph (constructed fromcreate_using
) with parallel edges.If
create_using
indicates an undirected multigraph, then only the edges indicated by the upper triangle of the matrixA
will be added to the graph.If the numpy matrix has a single data type for each matrix entry it will be converted to an appropriate Python data type.
If the numpy matrix has a user-specified compound data type the names of the data fields will be used as attribute keys in the resulting NetworkX graph.
Examples
Simple integer weights on edges:
>>> import numpy as np >>> A = np.array([[1, 1], [2, 1]]) >>> G = nx.from_numpy_matrix(A)
If
create_using
indicates a multigraph and the matrix has only integer entries andparallel_edges
is False, then the entries will be treated as weights for edges joining the nodes (without creating parallel edges):>>> A = np.array([[1, 1], [1, 2]]) >>> G = nx.from_numpy_matrix(A, create_using=nx.MultiGraph) >>> G[1][1] AtlasView({0: {'weight': 2}})
If
create_using
indicates a multigraph and the matrix has only integer entries andparallel_edges
is True, then the entries will be treated as the number of parallel edges joining those two vertices:>>> A = np.array([[1, 1], [1, 2]]) >>> temp = nx.MultiGraph() >>> G = nx.from_numpy_matrix(A, parallel_edges=True, create_using=temp) >>> G[1][1] AtlasView({0: {'weight': 1}, 1: {'weight': 1}})
User defined compound data type on edges:
>>> dt = [("weight", float), ("cost", int)] >>> A = np.array([[(1.0, 2)]], dtype=dt) >>> G = nx.from_numpy_matrix(A) >>> list(G.edges()) [(0, 0)] >>> G[0][0]["cost"] 2 >>> G[0][0]["weight"] 1.0